10.5”
55
Percentage of Movement in a Cant Movement Types
5.6 %
TWISTING
01.-0.2 %
BENDING
Checks + Fissures
CUPPING
SAMPLE A This trunk is not pre-cut. Fissure developed along the shortest line between the heart and the bark. This is caused by tangential shrinkage.
SAMPLE B Pre-cut was done along the X line, which is the longest line from the heart to the bark. This caused fissure to open along the X line. This shows that strategic pre-cutting can induce major fissure to occur on the visually insignificant side.
BOWING
Connections
The conclusions drawn from the test frames were that metal fastening systems [ A ] would prove to rigid for a shrinking frame, and traditional mortise and tenon joints [ B ] were too labor intensive based on our criteria. The pegged lap joint [ C ] would prove to be the joint most accommodating to movement and least time consuming to assemble.
SAMPLE E Samples C, D, and E demonstrate the effects of removing of the center as a technique to minimize fissure reaching to the bark. The size of the holes get bigger from top to bottom.
[ B ] Traditional mortise and tenon
SAMPLE F Another demonstration of fissure along the shortest line from the heart to the exposed surface. Distortion is visible.
[ A ]
Typical steel plate connection [ C ] Half lap joint with wooden peg
Natural movement is a result in the drying process, but proves a challenge when considering a building’ s structural system. The components of the structural system must be oriented strategically to take advantage of the direction of wood to reach higher degrees of stability. This orientation must be considered when considering an overall system as well as when designing each particular joint.